几何光学在考纲中共有五个知识点,在高 考中常以选择题的形式出现.试题不难,只要认 真复习就能顺利应考.本文对此作一个介绍. 1.光的直线传播 实例:影的形成(本影、半影)、日食、月食、小 孔成像等. 例1 一路灯距地面的高度为h,身高为l 的人以速度v匀速行走,如图1所示. (1)试证明人的头顶的影子做匀速运动; (2)求人影的长度随时间的变化率. There are five knowledge points in the syllabus of geometric optics, and often appear in the form of multiple choice questions in the college entrance examination. The test questions are not difficult, as long as careful review can be successfully applied. This article makes an introduction to this. 1. The linear propagation of light examples: shadow of Formation (umbra, penumbra), solar eclipse, lunar eclipse, small hole imaging, etc. Example 1 The height of a street lamp from the ground is h, and the person with a height of l walks at a uniform speed v, as shown in Figure 1. (1 ) Try to prove that the shadow of the person’s head does a uniform movement; (2) seek the rate of change in the length of the shadow over time.